package net.lzzy.gitdemo;

import java.io.*;

public class Java_demo4 {
    public static void main(String[] args) throws IOException{
        if (args.length !=2){
            System.out.println(
                    "Usage:java Copy sourceFile targetfile"
            );
            System.exit(1);
        }
        File sourceFile = new File(args[0]);
        if (!sourceFile.exists()){
            System.out.println("Taget file"+args[0]
                    + "does not exist");
            System.exit(2);
        }

        File targetFile = new File(args[1]);
        if(targetFile.exists()){
            System.out.println("Target file"+args[1]+"already exists");
            System.exit(3);
        }

        try(
                BufferedInputStream input =
                        new BufferedInputStream(new FileInputStream(sourceFile));
                BufferedOutputStream output=
                        new BufferedOutputStream(new FileOutputStream(targetFile))
        ){
            int r,numberOfBytesCopied=0;
            while ((r = input.read()) !=-1){
                output.write((byte)r);
                numberOfBytesCopied++;
        }
            System.out.println(numberOfBytesCopied + "bytes copied");
        }
    }
}
